My first post, go easy. I have a couple of arduino UNO boards and looking for something to monitor the chemical levels in my pool.I want to do it using least amount of power, ie low power mode and I am having a pretty hard time finding probes or sensors.

I want to have a floating gadget in the pool; on its bottom-side would be multiple electrode/probes that measure different chemical levels. So the probes I am looking for would have to last a looooong time submerged in later, and live through hot and cold days through and through.

I imagine many pool owners here would be interested in having this gadget?

These are the sensors/probes I had in mind:temperature - not worried should be able to find easilyph levelfree chlorinebromine (for salt water pool)

would be cool if I could find these:TDS (total dissoved solids)SaltAlkalinityCyanuric Acid

Ideas on sourcing these sensors? Anyone interested in a similar project would be great!

Apart from temperature, the main thing you can measure in water, is electrical conductivity. For specific applications, you can draw conclusions from the measuredelectrical conductivity based on known relationships between conductivity and concentrationof anions and cations in the water. But you cannot easily determine which anions andcations.

You can also measure pH, which has some complications and requires calibration.

To detect other things, you are usually looking at some kind of characteristic chemicalreaction ( such as silver with chloride ions ), which is difficult to do with a "probe".

I've got a pool, but honestly, some of those measurements are likely to involve sensors costing thousands of dollars.

I would be most happy to be proved wrong.

A quick search reveals a number of web sites that supply sensors such as Cynanuric Acid sensors. Rather alarmingly, I haven't found a price quoted. I'm reminded of the quote: "if you have to ask how much it is, you can't afford it" which is code for "it's very expensive".

Please post technical questions on the forum, not by personal message. Thanks!

These would be cool:A way to detect the water level - maybe the anchor being permanently on the bottom could have a REALLY accurate depth sensor or maybe a couple of magnets attached to the side of the pool and the floating lab can work out the level using a magnetic sensor? Chlorine level - these sensors appear to be expensive, so probably too hard?A way to detect the force of water coming out of the main pump outlet (to tell you the skimmer is blocked, the sand filter needs a backwash or the pump has issues) - the floating lab could be anchored next to the outlet and there could be a paddle that is moved by the water?

I hope i get this right:I dont think pH sensors are usually made for permanently exposing them to the substance u want to measure, as the tip usually has to get put a solution of KCl, also measurement isnt like just reading some stuff with analog in , you also need measurement bridges (hope thats the english term) and to amplify, as they have usually just changes in milivolts, and as it has been said continious calibration is an issue. And thats only pH...

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